Imaging device and focus control method

ABSTRACT

An imaging device, includes: a sensor including first phase difference detecting pixels arranged in a row direction and second phase difference detecting pixels arranged in the row direction; a defocus amount calculating unit which calculates a correlated amount of a first output signal group and a second output signal group while shifting the first output signal group and the second output signal group in the row direction by an arbitrary amount to calculate a defocus amount from a first shift amount of the first output signal group and the second output signal group when the correlated amount is at a maximum. The defocus amount calculating unit changes an upper limit of a shift amount of the first output signal group and the second output signal group in accordance with at least one of an F value, a focal distance, and a position of a focus lens.

CROSS REFERENCE TO RELATED APPLICATION

This is a continuation of International Application No.PCT/JP2013/065022 filed on May 30, 2013, and claims priority fromJapanese Patent Application No. 2012-196094, filed on Sep. 6, 2012, theentire disclosures of which are incorporated herein by reference.

BACKGROUND

1. Technical Field

The present invention relates to an imaging device and a focus controlmethod.

2. Related Art

Recently, as the resolution of a solid-state imaging element such as acharge coupled device (CCD) image sensor and a complementary metal oxidesemiconductor (CMOS) image sensor becomes higher, a demand for aninformation device having a photographing function such as a digitalstill camera, a digital video camera, a cellular phone such as a smartphone, and a personal digital assistant (PDA) is rapidly increasing. Inthe meantime, the information device having an imaging function asdescribed above is referred to as an imaging device.

In such an imaging device, as a focus control method which focuses on amajor subject, a contrast auto focus (AF) method or a phase differenceAF method is employed. Since the phase difference AF method may detect afocusing position with high precision at a high speed as compared withthe contrast AF method, the phase difference AF method is widelyemployed in various imaging devices (see, e.g., Patent Literature 1(JP-A-2007-219539), Patent Literature 2 (JP-A-7-143391) and PatentLiterature 3 (JP-A-2009-92824)).

In the phase difference AF method, outputs of a pair of phase detectingsensor rows are obtained as data and correlation of the outputs of thepair of sensor rows is obtained. Specifically, data of one of the sensorrows is assumed as A[1] A[k] and data of the other sensor row is assumedas B[1] B[k] and a value of “d” when an area S[d] enclosed by two datawaveforms calculated by the following equation when the two data isdisplaced by “d” is at a minimum is calculated as a phase differenceamount and a focus lens is driven based on the phase difference amount.

$\begin{matrix}{\left\lbrack {{Equation}\mspace{14mu} 1} \right\rbrack\mspace{619mu}} & \; \\{{{S\lbrack d\rbrack} = {\sum\limits_{n = 1}^{k}\left( {{A\left\lbrack {n + d} \right\rbrack} - {B\lbrack n\rbrack}} \right)^{2}}}{{d = {- L}},\ldots\mspace{14mu},{- 2},{- 1},0,1,2,\ldots\mspace{14mu},L}} & (1)\end{matrix}$

Patent Literature 1 discloses an imaging device which performs anoptimal focus operation on a photosensitive member by changing a shiftpitch (corresponding to an amount of change of d) of two images whencorrelation of two images formed on the pair of phase differencedetecting sensors is operated in accordance with information(information on a permissible circle diameter of confusion) on thephotosensitive member (a film or an imaging element) of a camera mainbody.

Patent Literature 2 discloses an imaging device which calculates a phasedifference amount having L in Equation 1 as a first value, recalculatesthe phase difference amount by decreasing L to be smaller than the firstvalue after moving the focus lens based on the phase difference amount,and moves the focus lens based on the phase difference amount.

Patent Literature 3 discloses an imaging device which varies a width ofthe phase difference detecting sensor row which is used to calculate thephase difference amount in accordance with a zoom magnification.

SUMMARY OF INVENTION

According to the imaging device disclosed in Patent Literatures 1 to 3,precision of the phase difference AF may be improved. However, redundantoperation may be performed for the phase difference AF so that it cannotsay that the operation for the phase difference AF is efficientlyperformed.

For example, when a subject which is slightly blurred and a subjectwhich is significantly blurred are compared, the value of L of thesubject which is slightly blurred becomes smaller than that of thesubject which is significantly blurred. However, in Patent Literatures 1and 3, regardless of the state of the subject, L is constant, so thatthe correlation operation may be unnecessarily performed.

In Patent Literature 2, even though the value of L is changed at thetime of first correlation operation and second correlation operation,since the value of L is fixed in each correlation operation regardlessof the state of the subject, the correlation operation may beunnecessarily performed.

In view of above, an object of the present invention is to provide animaging device and a focus control method which may increase a speed ofa phase difference AF by efficiently performing an operation of thephase difference amount.

An aspect of the present invention provides an imaging device,including: a sensor including a plurality of first phase differencedetecting pixels which receives one of a pair of luminous fluxes whichhave passed through different parts of a pupil area of an imagingoptical system and is arranged in a row direction and a plurality ofsecond phase difference detecting pixels which receives the other one ofthe pair of luminous fluxes and is arranged in the row direction; adefocus amount calculating unit which calculates a correlated amount ofa first output signal group and a second output signal group whileshifting the first output signal group of the plurality of first phasedifference detecting pixels and the second output signal group of theplurality of second phase difference detecting pixels in the rowdirection by an arbitrary amount to calculate a defocus amount from afirst shift amount of the first output signal group and the secondoutput signal group when the correlated amount is at a maximum; and afocus control unit which controls a focus state of the imaging opticalsystem based on the defocus amount, in which the defocus amountcalculating unit changes an upper limit of a shift amount of the firstoutput signal group and the second output signal group in accordancewith at least one of an F value of the imaging optical system, a focaldistance of the imaging optical system, and a position of a focus lensincluded in the imaging optical system.

Another aspect of the present invention provides a focus control methodby an imaging device which includes a sensor including a plurality offirst phase difference detecting pixels which receives one of a pair ofluminous fluxes which have passed through different parts of a pupilarea of an imaging optical system and is arranged in a row direction anda plurality of second phase difference detecting pixels which receivesthe other one of the pair of luminous fluxes and is arranged in the rowdirection, the method including: a defocus amount calculating step ofcalculating a correlated amount of a first output signal group and asecond output signal group while shifting the first output signal groupof the plurality of first phase difference detecting pixels and thesecond output signal group of the plurality of second phase differencedetecting pixels in the row direction by an arbitrary shift amount tocalculate a defocus amount from a shifted mount of the first outputsignal group and the second output signal group when the correlatedamount is at a maximum; and a focus control step of controlling a focusstate of the imaging optical system based on the defocus amount, inwhich in the defocus amount calculating step, an upper limit of a shiftamount of the first output signal group and the second output signalgroup is changed in accordance with at least one of an F value of theimaging optical system, a focal distance of the imaging optical system,and a position of a focus lens included in the imaging optical system.

Another aspect of the present invention provides an imaging device,including: an imaging element which includes a plurality of pixels whichis two dimensionally arranged in a row direction and a column directionwhich is perpendicular to the row direction, the plurality of pixelsincluding a plurality of imaging pixels which receives luminous fluxeswhich have passed through a pupil area of an imaging optical system, aplurality of first phase difference detecting pixels which receives oneof a pair of luminous fluxes which have passed through different partsof the pupil area of the imaging optical system, and a plurality ofsecond phase difference detecting pixels which receives the other one ofthe pair of luminous fluxes; a driving unit which performs rollingshutter driving to change an exposure period for every row of the pixelsto read out a signal in accordance with a light receiving amount duringthe exposure from the pixels included in each row; a defocus amountcalculating unit which calculates a correlated amount of a first outputsignal group and a second output signal group while shifting the firstoutput signal group of the plurality of first phase difference detectingpixels which is included in one of two adjacent rows among rows of thepixels and a second output signal group of the plurality of second phasedifference detecting pixels which is included in the other one of thetwo rows in the row direction by an arbitrary amount to calculate adefocus amount from a first shift amount of the first output signalgroup and the second output signal group when the correlated amount isat a maximum; a focus control unit which controls a focus state of theimaging optical system based on the defocus amount; and a shift amountcalculating unit which calculates a second shift amount of the firstoutput signal group and the second output signal group in the rowdirection caused by the rolling shutter driving, from a shift amount ofthe output signal groups in the row direction when a correlated amountbetween the output signal groups of the plurality of imaging pixelsincluded in two adjacent rows among the rows of the pixels is at themaximum, in which the defocus amount calculating unit changes an upperlimit of the shift amount of the first output signal group and thesecond output signal group in accordance with the second shift amount.

Another aspect of the present invention provides a focus control methodby an imaging device which includes an imaging element which includes aplurality of pixels which is two dimensionally arranged in a rowdirection and a column direction which is perpendicular to the rowdirection, the plurality of pixels including a plurality of imagingpixels which receives luminous fluxes which have passed through a pupilarea of an imaging optical system, a plurality of first phase differencedetecting pixels which receives one of a pair of luminous fluxes whichhave passed through different parts of the pupil area of the imagingoptical system, and a plurality of second phase difference detectingpixels which receives the other one of the pair of luminous fluxes, themethod including: a driving step of performing rolling shutter drivingto change an exposure period for every row of pixels to read out asignal in accordance with a light receiving amount during the exposurefrom the pixels included in each row; a defocus amount calculating stepof calculating a correlated amount of a first output signal group and asecond output signal group while shifting the first output signal groupof the plurality of first phase difference detecting pixels which isincluded in one of two adjacent rows among rows of the pixels and asecond output signal group of the plurality of second phase differencedetecting pixels which is included in the other one of the two rows inthe row direction by an arbitrary amount to calculate a defocus amountfrom a first shift amount of the first output signal group and thesecond output signal group when the correlated amount is at a maximum; afocus control step of controlling a focus state of the imaging opticalsystem based on the defocus amount; and a shift amount calculating stepof calculating a second shift amount of the first output signal groupand the second output signal group in the row direction caused by therolling shutter driving, from a shift amount of the output signal groupsin the row direction when a correlated amount of the output signalgroups of the plurality of imaging pixels included in two adjacent rowsamong the rows of pixels is at the maximum, in which in the defocusamount calculating step, an upper limit of the shift amount of the firstoutput signal group and the second output signal group is changed inaccordance with the second shift amount.

Any one of the aspects of the present invention may efficiently performan operation of a phase difference amount to achieve high speed phasedifference AF.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating a schematic configuration of a digitalcamera as an example of an imaging device for explaining an embodimentof the present invention.

FIG. 2 is a schematic plan view illustrating a configuration of asolid-state imaging element 5 which is mounted in the digital cameraillustrated in FIG. 1.

FIG. 3 is a view illustrating an example of two pixel rows which is usedfor correlation operation, in the solid-state imaging element 5illustrated in FIG. 2.

FIG. 4 is a view illustrating an example of a table which is stored in amain memory of the digital camera illustrated in FIG. 1.

FIG. 5 is a flow chart for explaining an operation of the digital cameraillustrated in FIG. 1.

FIG. 6 is a flow chart for explaining a modified embodiment of a phasedifference AF operation of the digital camera illustrated in FIG. 1.

FIG. 7 is a view illustrating a solid-state imaging element 5 a which isa modified embodiment of the solid-state imaging element 5 illustratedin FIG. 2.

FIG. 8 is a view explaining a smart phone as an imaging device.

FIG. 9 is an internal block diagram of the smart phone of FIG. 8.

DESCRIPTION OF EMBODIMENTS

Hereinafter, an embodiment of the present invention will be describedwith reference to the drawings.

FIG. 1 is a diagram illustrating a schematic configuration of a digitalcamera as an example of an imaging device for explaining an embodimentof the present invention.

An imaging system of a digital camera illustrated in FIG. 1 includes alens device (including a photographing lens 1 and a diaphragm 2) as animaging optical system and a CMOS solid-state imaging element 5.

The lens device including the photographing lens 1 and the diaphragm 2may be detachable from a camera main body or fixed to the camera mainbody. The photographing lens 1 includes a focus lens and a zoom lens.The focus lens refers to a lens which moves in a direction of an opticalaxis to adjust a focus position. The zoom lens refers to a lens whichmoves in the direction of the optical axis to change a focal distanceand change an imaging angle of view. The imaging angle of view is arange which is captured by the imaging element and represented as anangle. Further, the focal distance refers to a distance from the lens tothe imaging element when the focus is adjusted.

A system control unit 11 which collectively controls an entireelectrical control system of the digital camera controls a flash lightemitting unit 12 and a light receiving unit 13. Further, the systemcontrol unit 11 controls a lens driving unit 8 to adjust a position of afocus lens which is included in the photographing lens 1 or a positionof the zoom lens which is included in the photographing lens 1.Moreover, the system control unit 11 controls an aperture size of thediaphragm 2 through a diaphragm driving unit 9 so as to adjust anexposure amount.

The system control unit 11 drives the solid-state imaging element 5through an imaging element driving unit 10 to output a subject imagecaptured through the photographing lens 1 as a captured image signal. Aninstruction signal from a user is input to the system control unit 11through an operating unit 14.

The electrical control system of the digital camera further includes ananalog signal processing unit 6 connected to an output of thesolid-state imaging element 5 to perform an analog signal processingsuch as a correlated double sampling processing and an A/D convertingcircuit 7 which converts an analog signal output from the analog signalprocessing unit 6 into a digital signal. The analog signal processingunit 6 and the A/D converting circuit 7 are controlled by the systemcontrol unit 11. The analog signal processing unit 6 and the A/Dconverting circuit 7 may be embedded in the solid-state imaging element5 in some cases.

The electrical control system of the digital camera includes a mainmemory 16, a memory control unit 15 which is connected to the mainmemory 16, a digital signal processing unit 17 which performs aninterpolation operation, a gamma correction operation, and an RGB/YCconversion processing on a captured image signal output from the A/Dconverting circuit 7 to generate photographed image data, a compressionand decompression processing unit 18 which decompresses the photographedimage data generated in the digital signal processing unit 17 in a JPEGformat or expands the compressed image data, a defocus amountcalculating unit 19 which calculates a defocus amount, an externalmemory control unit 20 to which a detachable recording medium 21 isconnected, and a display control unit 22 to which a display unit 23mounted on a rear surface of a camera is connected. The memory controlunit 15, the digital signal processing unit 17, the compression andexpansion processing unit 18, the defocus amount calculating unit 19,the external memory control unit 20, and the display control unit 22 areconnected to each other through a control bus 24 and a data bus 25 to becontrolled by a command from the system control unit 11.

FIG. 2 is a schematic plan view illustrating a configuration of asolid-state imaging element 5 which is mounted in the digital cameraillustrated in FIG. 1.

The solid-state imaging element 5 includes a plurality of pixels 51(square blocks in the drawing) which is two-dimensionally arranged in arow direction X and a column direction Y, which is perpendicular to therow direction X. Even though all pixels 51 are not illustrated in FIG.2, actually, millions to tens of millions of pixels 51 aretwo-dimensionally arranged. When an image is captured by a solid-stateimaging element 5, output signals from a plurality of pixels 51 areindividually obtained. A set of the plurality of output signals isreferred to as a captured image signal in this specification.

Each pixel 51 includes a photoelectric converting unit such as aphotodiode, a color filter which is formed above the photoelectricconverting unit, and a signal output circuit which outputs a signal inaccordance with signal charges which are accumulated in thephotoelectric converting unit.

The signal output circuit is a well-known MOS circuit and, for example,is configured to include a charge accumulating unit to which chargesaccumulated in the photoelectric converting unit are transmitted, atransfer transistor which transfers the charges of the photoelectricconverting unit to the charge accumulating unit, a reset transistorwhich resets a potential of the charge accumulating unit, an outputtransistor which outputs a signal in accordance with the potential ofthe charge accumulating unit, and a row selecting transistor whichselectively outputs a signal from the output transistor to an outputsignal line.

In FIG. 2, a pixel 51 including a color filter which transmits a redlight component is denoted by a reference character “R”, a pixel 51including a color filter which transmits a green light component isdenoted by a reference character “G”, and a pixel 50 including a colorfilter which transmits a blue light component is denoted by a referencecharacter “B”.

An arrangement of the plurality of pixels 51 is configured such that aplurality of pixel rows including a plurality of pixels 51 which islined up in a row direction X is lined up in a column direction Y. Oddnumbered pixel rows and even numbered pixel rows are off-centered byapproximately a half of an arrangement pitch of the pixels 51 of eachpixel row in the row direction X.

The color filters which are included in each pixel 51 of an odd-numberedpixel row are entirely arranged in a Bayer arrangement. Further thecolor filters which are included in each pixel 51 of an even-numberedpixel row are also entirely arranged in a Bayer arrangement. A pixel 51in the odd-numbered row and a pixel 51 which detects the same colorlight component as the pixel 51 and is adjacent to the pixel 51 at alower right side form a pair pixel.

According to the solid-state imaging element 5 having such a pixelarrangement, output signals of two pixels 51 which form the pair pixelare added to achieve a high sensitivity camera or exposure times of thetwo pixels 51 which configure the pair pixel are changed and outputsignals of the two pixels 51 are added to achieve a wide dynamic rangeof a camera.

In the solid-state imaging element 5, some of the plurality of pixels 51serve as phase difference detecting pixels.

The phase difference detecting pixels include a plurality of phasedifference detecting pixels 51R and a plurality of phase differencedetecting pixels 51L.

The plurality of phase difference detecting pixels 51R receives one (forexample, a luminous flux which has passed through a right half of thepupil area) of a pair of luminous fluxes which have passed throughdifferent parts of a pupil area of the photographing lens 1 and outputsa signal in accordance with an amount of received light. That is, theplurality of phase difference detecting pixels 51R provided in thesolid-state imaging element 5 captures an image formed by one of thepair of luminous fluxes which have passed through different parts of thepupil area of the photographing lens 1.

The plurality of phase difference detecting pixels 51L receives theother one (for example, a luminous flux which has passed through a lefthalf of the pupil area) of the pair of luminous fluxes and outputs asignal in accordance with an amount of received light. That is, theplurality of phase difference detecting pixels 51L provided in thesolid-state imaging element 5 captures an image formed by the other oneof the pair of luminous fluxes which have passed through different partsof the pupil area of the photographing lens 1.

In the meantime, a plurality of pixels 51 (hereinafter, referred to asimaging pixels) other than the phase difference detecting pixels 51R and51L captures an image formed by a luminous flux which passes throughalmost all parts of the pupil area of the photographing lens 1.

A light shielding layer is provided above the photoelectric convertingunit of the pixel 51 and an opening which defines a light receiving areaof the photoelectric converting unit is formed in the light shieldinglayer.

A center of the opening (denoted by reference character “a” in FIG. 2)of the imaging pixel 51 coincides with a center (a center of a squareblock) of the photoelectric converting unit of the imaging pixel 51. Inthe meantime, in FIG. 2, in order to simplify the drawing, the opening ais illustrated only in a part of the imaging pixels 51.

To the contrary, a center of an opening (denoted by reference character“c” in FIG. 2) of the phase difference detecting pixel 51R isoff-centered to the right with respect to the center of thephotoelectric converting unit of the phase difference detecting pixel51R.

A center of an opening (denoted by reference character “b” in FIG. 2) ofthe phase difference detecting pixel 51L is off-centered to the leftwith respect to the center of the photoelectric converting unit of thephase difference detecting pixel 51L.

In the solid-state imaging element 5, a part of the pixels 51 on which agreen color filter is mounted serve as the phase difference detectingpixels 51R or the phase difference detecting pixels 51L. Of course, apixel on which other color filter is mounted may serve as the phasedifference detecting pixel.

The phase difference detecting pixel 51R and the phase differencedetecting pixel 51L are discretely and periodically arranged in a regionwhere the pixels 51 are disposed.

The phase difference detecting pixels 51R are disposed at intervals ofthree pixels 51 in the row direction X in a part (four pixel rows whichare lined up at intervals of three pixel rows in the example of FIG. 2)of the even-numbered pixel rows, in the example of FIG. 2.

In the example of FIG. 2, the phase difference detecting pixels 51L aredisposed with the same cycle as the phase difference detecting pixels51R in the row direction X in the part (a pixel row next to the pixelrow including the phase difference detecting pixel 51R) of theodd-numbered pixel rows.

With this configuration, among light components which pass through theopening b of the light shielding layer to be received by the pixel 51L,a light component which is received from the left side as seen from asubject of the photographing lens 1 provided on an upper portion of thesheet of FIG. 2, that is, a light component which enters from adirection where the subject is watched with a right eye becomes a maincomponent. Further, among light components which pass through theopening c of the light shielding layer to be received by the pixel 51R,a light component which is received from the right side as seen from thesubject of the photographing lens 1, that is, a light component whichenters from a direction where the subject is watched with a left eyebecomes a main component.

That is, a captured image signal which is obtained by seeing the subjectwith the left eye may be obtained by all the phase difference detectingpixels 51R and a captured image signal which is obtained by seeing thesubject with the right eye may be obtained by all the phase differencedetecting pixels 51L. Therefore, stereoscopic image data of the subjectmay be generated by combining both the image signals or phase differenceamount may be calculated by correlating both the image signals.

In the meantime, the phase difference detecting pixel 51R and the phasedifference detecting pixel 51L are adapted to cause the opening of thelight shielding layer to be off-centered in a reverse direction toreceive the luminous fluxes which pass through the different parts ofthe pupil area of the photographing lens 1 to obtain a phase differenceamount. However, a structure for obtaining the phase difference amountis not limited thereto, but other known structures may be employed.

The solid-state imaging element 5 further includes a vertical scanningcircuit 52 and a horizontal scanning circuit 53.

The vertical scanning circuit 52 controls to turn on/off a transfertransistor, a reset transistor, and a row selecting transistor of asignal output circuit which is included in each pixel 51.

The horizontal scanning circuit 53 is connected to an output signal linewhich is provided for every pixel column which is formed by pixels 51which are parallel to each other in the column direction Y andsequentially outputs an output signal, which is output from each pixel51 in the pixel row to the output signal line, to the outside of thesolid-state imaging element 5.

The vertical scanning circuit 52 and the horizontal scanning circuit 53operate in accordance with an instruction of the imaging element drivingunit 10 illustrated in FIG. 1. The imaging element driving unit 10drives the solid-state imaging element 5 by a so-called rolling shuttermethod in which every pixel row is shifted to be exposed by apredetermined time.

An exposure period of each pixel 51 of the pixel row starts at a timewhen the reset transistor of each pixel 51 is turned on and a potentialof the charge accumulating unit which is included in each pixel 51 isreset and ends at a time when the transfer transistor which is includedin each pixel 51 is turned on and the charges accumulated in thephotoelectric converting unit of each pixel 51 are completelytransmitted to the charge accumulating unit. The imaging element drivingunit 10 controls the vertical scanning circuit 52 so that startingtimings of the exposure period vary at every pixel row.

The defocus amount calculating unit 19 illustrated in FIG. 1 uses anoutput signal group read out from the phase difference detecting pixel51L and the phase difference detecting pixel 51R to calculate a phasedifference amount which is a relative off-centered amount of two imagesformed by the pair of luminous fluxes. The defocus amount calculatingunit 19 calculates a focus adjusted state of the photographing lens 1,in this case, an amount by which the photographing lens 1 deviates froma focused state and a direction thereof, that is, a defocus amount,based on the phase difference amount.

The system control unit 11 illustrated in FIG. 1 moves a focus lensincluded in the photographing lens 1 to a focus position based on thedefocus amount calculated by the defocus amount calculating unit 19 tocontrol the focused state of the photographing lens 1.

Next, a method of calculating a phase difference amount by the defocusamount calculating unit 19 will be described in detail.

The defocus amount calculating unit 19 calculates the phase differenceamount using output signals read out from two pixel rows of the pixelrow including the phase difference detecting pixels 51R and the pixelrow including the phase difference detecting pixels 51L which areadjacent to the phase difference detecting pixels 51R.

In the meantime, in this specification, two adjacent pixels (or pixelrows) refer to two pixels (or pixel rows) which are adjacent to eachother such an extent that the light is received from the substantiallysame subject part.

In a signal group output from two adjacent pixel rows (a pixel row L1and a pixel row L2) enclosed by a thick line in FIG. 3, the defocusamount calculating unit 19 sequentially denotes output signals of thephase difference detecting pixels 51R included in the pixel row L1 asA[1], . . . , A[k] from the left in the row direction X of the phasedifference detecting pixels 51R.

The defocus amount calculating unit 19 sequentially denotes outputsignals of the phase difference detecting pixels 51L included in thepixel row L2 as B[1], . . . , B[k] from the left in the row direction Xof the phase difference detecting pixels 51L.

A signal A[n] and a signal B[n] (n=1, 2, 3, . . . , k) are outputsignals of the adjacent phase difference detecting pixel 51R and phasedifference detecting pixel 51L (the phase difference detecting pixel 51Rand the phase difference detecting pixel 51L which form a pair pixel).

The defocus amount calculating unit 19 calculates an area S[d]corresponding a correlated amount of an image (corresponding to anoutput signal group of a plurality of phase difference detecting pixels51L included in the pixel row L1) captured by the phase differencedetecting pixels 51L of the pixel row L1 and an image (corresponding toan output signal group of a plurality of phase difference detectingpixels 51R included in the pixel row L2) captured by the phasedifference detecting pixel 51R of the pixel row L2 by operation of aboveEquation 1. It means that as a value of the area S[d] is smaller, acorrelated amount of the two images is larger.

The defocus amount calculating unit 19 calculates a value of “d” whenamong all S[d] obtained by incrementing a value of “d” in Equation 1 byunit amount (for example, “1”, which is arbitrarily determined) in arange of L to −L, S[d] has a minimum value (in other words, thecorrelated amount of the two images is at a maximum), as the phasedifference amount.

In the embodiment, in order to optimize a computational amount of acorrelation operation by Equation 1, the defocus amount calculating unit19 changes the value of L (a positive upper limit which shifts twoimages when the correlation operation is performed. Hereinafter,referred to as a shift amount) in accordance with an F value of thediaphragm 2, a focal distance (a position of the zoom lens) of thephotographing lens 1, and a position (a focus position) of the focuslens included in the photographing lens 1. The F value is a value (whichbecomes smaller at a diaphragm opening side) determined by an aperturesize of the diaphragm.

It is determined whether the subject is significantly blurred orslightly blurred by the combination of the F value, the focal distance,and the focus position. When the subject is slightly blurred, the phasedifference amount d becomes smaller as compared with a situation whenthe subject is significantly blurred.

Therefore, the defocus amount calculating unit 19 makes a value of theshift amount L when the subject is slightly blurred smaller than a valueof the shift amount when the subject is significantly blurred. By doingthis, the number of operations for S[d] in Equation 1 is reduced, sothat an unnecessary operation may be omitted.

A relationship between the combination of the F value and the focaldistance and the shift amount L is experimentally obtained in advanceand a table illustrated in FIG. 4 is previously stored in the mainmemory 16. In the meantime, the table illustrated in FIG. 4 is a tablewhen the focus position is at an MOD or INF (both ends of the focus lensin a movable range).

When it is assumed that a movement amount from an end of the focus lensto the other end is M and a variation of the defocus amount when thefocus lens moves by the movement amount M is Md, a maximum value whichis capable of being set as the shift amount L is obtained by backcalculating the phase difference amount from the variation Md. Since thetable illustrated in FIG. 4 is a table when the focus position is at anMOD or INF, L=96 is a maximum value of the shift amount L which iscapable of being set by the defocus amount calculating unit 19.

As the F value is increased, blurring of the subject is reduced(separation of the image is reduced), so that even though the movementamounts of the focus lens required for focusing are equal, the phasedifference amount is reduced. Further, as the focal distance isdecreased, blurring of the subject is reduced (separation of the imageis reduced), so that even though the movement amounts of the focus lensrequired for focusing are equal, the phase difference amount is reduced.

As described above, in accordance with the combination of the F valueand the focal distance, a maximum value of the phase difference amountvaries.

Therefore, as illustrated in FIG. 4, a table in which a value of theshift amount L corresponding to the maximum value of the phasedifference amount varies depending on the combination of the F value andthe focal distance may be created.

In the meantime, a value (hereinafter, also referred to as a requiredfocus movement amount) which is minimally required for the movementamount of the focus lens has M as an upper limit when the focus positionis at the MOD and the INF. However, when the focus position is betweenthe MOD and the INF, the upper limit of the required focus movementamount becomes smaller than M.

For example, when the focus position is in the middle of the MOD and theINF, the required focus movement amount is M/2 at maximum. Therefore, inthis case, even when each numerical value of L in the table illustratedin FIG. 4 is halved, the focus control may be performed withoutincurring any problems.

The defocus amount calculating unit 19 determines a maximum value of therequired focus movement amount from focus position information at a timewhen the phase difference AF is performed and processes a tableillustrated in FIG. 4 in accordance with the determined maximum todetermine the shift amount L.

Specifically, the defocus amount calculating unit 19 calculates adistance between the current position of the focus lens and the MOD anda distance between the current position of the focus lens and the INF toconsider a larger one of the two distances as a maximum value Ma of therequired focus movement amount corresponding to all combinations of theF value and the focal distance. Further, the defocus amount calculatingunit 19 selects a numerical value corresponding to the combination ofthe F value and the focal distance obtained from the system control unit11, from the table of FIG. 4 to determine a value (rounding off to thenearest whole number) obtained by multiplying the numerical value andthe Ma/M as the shift amount L.

For example, when the focus position is in the middle of the middle ofthe INF and the MOD and the INF, the F value is F2.0 and the focaldistance is 56 or larger and smaller than 100, the defocus amountcalculating unit 19 determines 32×(¾)=24 as the shift amount L.

In the meantime, the table illustrated in FIG. 4 is created for everyfocus position and is stored in the main memory 16 and the defocusamount calculating unit 19 may determine the shift amount L from thetable corresponding to the focus position and the F value and the focalposition.

An operation of a digital camera configured as described above will bedescribed.

FIG. 5 is a flow chart for explaining a phase difference AF operation ofthe digital camera illustrated in FIG. 1.

When there is an instruction to perform a phase difference AF, imagingfor the phase difference AF is performed by the solid-state imagingelement 5 by the control of the system control unit 11 and the capturedimage signal output from the solid-state imaging element 5 by theimaging is stored in the main memory 16.

The defocus amount calculating unit 19 obtains information on an F valueof the diaphragm 2 at a time when there is the instruction to performthe phase difference AF, a focal distance determined by a position ofthe zoom lens, and a position of the focus lens from the system controlunit 11 (step S1).

Next, the defocus amount calculating unit 19 determines the shift amountL using the information obtained in step S1 and the table stored in themain memory 16 (step S2).

Next, the defocus amount calculating unit 19 obtains an output signalgroup of the phase difference detecting pixel 51L obtained from thepixel row L1 and an output signal group of the phase differencedetecting pixel 51R obtained from the pixel row L2 which are included inthe captured image signal stored in the main memory 16 (step S3).

Next, the defocus amount calculating unit 19 performs the correlationoperation represented in Equation 1 using the output signals obtained instep S3 (step S4). Here, as the shift amount L, a value determined instep S2 is used.

As a result of the correlation operation, the defocus amount calculatingunit 19 considers a value of “d” when the S[D] is at a minimum as thephase difference amount. The defocus amount calculating unit 19 performsthe processes of steps S3 and S4 for every two pixel rows including thephase difference detecting pixel 51R and the phase difference detectingpixel 51L which forms a pair pixel with the phase difference detectingpixel 51R to calculate a plurality of phase difference amounts.

The defocus amount calculating unit 19 calculates a defocus amount usingthe plurality of phase difference amounts (step S5). For example, thedefocus amount calculating unit 19 averages out the plurality of phasedifference amounts and calculates the defocus amount based on theaveraged phase difference amount.

When the defocus amount is calculated, the system control unit 11 drivesa position of the focus lens based on the defocus amount to control thefocus (step S6).

As described above, according to the digital camera illustrated in FIG.1, since the shift amount L is determined in accordance with the Fvalue, the focal distance, and the focus position, as compared with acase when the shift amount L is always fixed, it is possible to preventan unnecessary correlation operation from being performed, therebymaking it possible to perform the phase difference AF at a high speed.

Next, a modified embodiment of the digital camera illustrated in FIG. 1will be described.

First Modified Embodiment

In the digital camera illustrated in FIG. 1, the imaging element drivingunit 10 drives the solid-state imaging element 5 in a rolling shuttermanner. In the rolling shutter manner, exposure timings for every pixelrow are slightly shifted. Therefore, when the subject is moving, eventhough the two pixel rows are adjacent to each other, a distortion of animage caused by the rolling shutter driving may be formed between theoutput signal groups obtained from the two pixel rows as a phasedifference in some cases.

Therefore, when a phase difference D caused by the rolling shutterdriving is generated, even when S[D] is at a minimum in d=L or d=−L,actually, S[L+D] or S[−(L+D)] may be smaller than the minimum S[d].

Therefore, in the first modified embodiment, the defocus amountcalculating unit 19 calculates a shift amount L′ obtained by adding thephase difference D caused by the rolling shutter driving to the value ofthe shift amount L determined in accordance with the F value, the focaldistance, and the focus position and d where S[d] is at a minimum iscalculated as a phase difference amount by the following Equation 2. InEquation 2, upper limits of the shift amount of two images in Equation 1are substituted with L′.

$\begin{matrix}{\left\lbrack {{Equation}\mspace{14mu} 2} \right\rbrack\mspace{619mu}} & \; \\{{{S\lbrack d\rbrack} = {\sum\limits_{n = 1}^{k}\left( {{A\left\lbrack {n + d} \right\rbrack} - {B\lbrack n\rbrack}} \right)^{2}}}{{d = {- L^{’}}},\ldots\mspace{14mu},{- 2},{- 1},0,1,2,\ldots\mspace{14mu},L^{’}}} & (2)\end{matrix}$

The phase difference D may be obtained by correlation operation ofoutput signals of the imaging pixels 51 which are included in the twoadjacent pixel rows.

For example, the defocus amount calculating unit 19 assumes outputsignals of the imaging pixel 51 included in a pixel row L1 illustratedin FIG. 3 as E[1], E[k] and output signals of the imaging pixel 51included in a pixel row L2 as F[1], F[k] and calculates a value of dwhere S[d] calculated from the following Equation 3 is at a minimum as aphase difference D.

In the meantime, an upper limit La of the shift amount of two images inEquation 3 has been determined in advance by the number of pixel rowsbetween the pixel row of the output source of E[1], E[k] and the pixelrow of the output source of F[1], F[k] and a read-out speed of theimaging element. As the number becomes smaller and the read-out speedbecomes higher, the phase difference D becomes smaller, so that when thenumber becomes smaller and the read-out speed becomes higher, La may beset to be smaller.

$\begin{matrix}{\left\lbrack {{Equation}\mspace{14mu} 3} \right\rbrack\mspace{619mu}} & \; \\{{{S\lbrack d\rbrack} = {\sum\limits_{n = 1}^{k}\left( {{E\left\lbrack {n + d} \right\rbrack} - {F\lbrack n\rbrack}} \right)^{2}}}{{d = {{- L}\; a}},\ldots\mspace{14mu},{- 2},{- 1},0,1,2,\ldots\mspace{14mu},{L\; a}}} & (3)\end{matrix}$

FIG. 6 is a flow chart for explaining a modified embodiment of a phasedifference AF operation of the digital camera illustrated in FIG. 1. InFIG. 6, the same processings as those illustrated in FIG. 5 are denotedby the same reference numerals and descriptions thereof will be omitted.

Aster step S1, the defocus amount calculating unit 19 preliminarilydetermines the shift amount L using the information obtained in step S1and the table stored in the main memory 16 (step S10).

Next, the defocus amount calculating unit 19 obtains an output signalgroup of imaging pixels 51 obtained from the pixel row L1 and an outputsignal group of imaging pixels 51 obtained from the pixel row L2, amongthe captured image signals stored in the main memory 16 (step S11).

Next, the defocus amount calculating unit 19 calculates a phasedifference D by the rolling shutter, using two output signal groupsobtained in step S11 and Equation 3 (step S12).

Next, the defocus amount calculating unit 19 assumes a value obtained byadding the phase difference D calculated in step S12 to the shift amountL which is preliminarily determined in step S10 as a shift amount L′(step S13).

Next, the defocus amount calculating unit 19 performs the process ofstep S3 and operates Equation 2 using the output signal obtained in stepS3 and calculates d when S[d] is at a minimum as a phase differenceamount (step S14).

The defocus amount calculating unit 19 performs the processes of stepsS3 and S14 for every two pixel rows including the phase differencedetecting pixel 51R and the phase difference detecting pixel 51L whichforms a pair pixel with the phase difference detecting pixel 51R tocalculate a plurality of phase difference amounts.

The defocus amount calculating unit 19 calculates a defocus amount usingthe plurality of phase difference amounts (step S5). Next, the focuscontrol is performed based on the defocus amount (step S6).

As described above, according to the first modified embodiment, evenwhen distortion due to the rolling shutter driving occurs between twoimages which are targets for the correlation operation, the defocusamount may be precisely calculated.

In the meantime, in FIG. 6, in step S11 and step S3, output signalsobtained from all pixel rows L1 and L2 are obtained. By doing this, inthe case of phase difference AF, there is no need to read signals from apixel row other than the pixel row including the phase differencedetecting pixels 51R and 51L, that is, a pixel row including only theimaging pixel 51. Therefore, a signal used for the phase difference AFis read out at a high speed, so that high speed phase difference AF maybe achieved.

In the meantime, two output signal groups which are used to calculate aphase difference D due to the rolling shutter driving may be obtainedfrom the pixel row including only the imaging pixel 51.

For example, in step S11 of FIG. 6, the correlation operation may beperformed using output signal groups obtained from a pixel row L3 and apixel row L4 illustrated in FIG. 3 to calculate the phase difference D.

The two output signal groups which are used to calculate the phasedifference D may be obtained from two adjacent pixel rows and forexample, the phase difference D may be calculated using the outputsignal groups obtained from the pixel row L3 and the pixel row L5illustrated in FIG. 3.

In this case, the defocus amount calculating unit 19 obtains the valueof d when a left side of Equation 3 is at a minimum, as the phasedifference D and a value of D obtained here is four times of the phasedifference D calculated using the output signal groups obtained from thepixel row L3 and the pixel row L4. Therefore, a value obtained bydividing the value of d when the left side of Equation 3 is at a minimumby four becomes a final phase difference D.

In the meantime, in the first modified embodiment, the shift amount L ispreliminarily determined depending on the F value, the focal distance,and the focus position and then the phase difference D is added to theshift amount L to obtain the final shift amount L′.

However, the shift amount L to be preliminarily determined may be afixed value regardless of the F value, the focal distance, and the focusposition. In this case, even though the correlation operation may be notoptimized in accordance with the blurring state of the subject, thecorrelation operation may be performed in consideration of thedistortion of the image caused by the rolling shutter driving.Therefore, the precision of the phase difference AF may be improved.

In the meantime, in the above description, the rolling shutter drivingin which an exposure period varies is performed on all pixel rowsincluded in the solid-state imaging element 5. However, the rollingshutter driving may be performed only on a part of all pixel rows, thatis, on a row including the phase difference detecting pixels 51R and 51Land global shutter driving may be performed on the other pixel rows.

Until now, the pixels 51 are exemplified to be arranged in a so-calledhoney comb arrangement, but the present invention is applicable to asolid-state imaging element in which the pixels 51 are arranged in asquare lattice pattern.

FIG. 7 is a view illustrating a solid-state imaging element 5 a which isa modified embodiment of the solid-state imaging element 5 illustratedin FIG. 2.

A solid-state imaging element 5 a includes a plurality of pixels 51which is arranged in a square lattice pattern in a row direction X and acolumn direction Y, a vertical scanning circuit 52, and a horizontalscanning circuit 53. A configuration of the pixels 51′ is the same asthe configuration of the pixels 51 and an arrangement of the colorfilters is a Bayer arrangement.

The plurality of pixels 51′ includes normal pixels 51′ in which anopening a of a light shielding layer is not off-centered and phasedifference detecting pixels having off-centered openings d and e. Thepixel 51′ having the opening d corresponds to the phase differencedetecting pixel 51L and the pixel 51′ having the opening e correspondsto the phase difference detecting pixel 51R.

Also in the solid-state imaging element 5 a with the above-describedconfiguration, the shift amount L is determined by the above-describedmethod, so that the high speed phase difference AF may be performed.

In FIGS. 2 and 7, even though positions of the row direction of theadjacent phase difference detecting pixel 51R and phase differencedetecting pixel 51L are shifted by one pixel amount, the positions ofthe row direction of the adjacent phase difference detecting pixel 51Rand phase difference detecting pixel 51L may be the same.

Until now, even though the solid-state imaging elements 5 and 5 a havingmounted thereon color filters having a plurality of colors to performcolor imaging, the solid-state imaging elements 5 and 5 a may be animaging element for monochromic imaging in which a green filter which isa single color is mounted as the color filter or the color filter isomitted.

In an example other than the first modified embodiment, a CCD typesolid-state imaging element may be used as the solid-state imagingelement 5.

In the above description, the solid-state imaging element 5 serves as animaging element for imaging and phase difference detecting in which theimaging pixel 51 and the phase difference detecting pixels 51R and 51Lare mixed. However, the phase difference AF process illustrated in FIG.5 may be performed by providing an exclusive element for the phasedifference AF which does not have the imaging pixel 51 in the cameraseparately from the solid-state imaging element 5 and using an outputsignal from this element.

In the above description, the defocus amount calculating unit 19determines a shift amount L in accordance with the F value, the focaldistance, and the focus position. However, even though the defocusamount calculating unit 19 is configured to determine the shift amount Lin accordance with one of them, the operation for phase difference AFmay be efficiently performed.

In this specification, the digital camera is exemplified as the imagingdevice, but an embodiment of a smart phone including a camera as animaging device will be described below.

FIG. 8 illustrates an outer appearance of a smart phone 200 which is anembodiment of a photographing device of the present invention. The smartphone 200 illustrated in FIG. 8 includes a flat panel type housing 201and is provided, on one surface of the housing 201, with a display inputunit 204 in which a display panel 202 as a display unit, and anoperating panel 203 as an input unit are integrated. In addition, thehousing 201 includes a speaker 205, a microphone 206, an operating unit207, and a camera 208. However, a configuration of the housing 201 isnot limited thereto. For example, a configuration in which the displayunit and the input unit are independent from each other may be employedor a configuration having a folding structure or a slide mechanism maybe employed.

FIG. 9 is a block diagram illustrating a configuration of the smartphone 200 illustrated in FIG. 8. As illustrated in FIG. 8, as maincomponents, the smart phone includes a wireless communication unit 210,a display input unit 204, a calling unit 211, an operating unit 207, acamera 208, a storing unit 212, an external input/output unit 213, aglobal positioning system (GPS) receiving unit 214, a motion sensor unit215, a power supply 216, and a main control unit 220. Further, as a mainfunction of the smart phone 200, the smart phone 200 is provided with awireless communication function which performs mobile wirelesscommunication through a base station device BS which is not illustratedand a mobile communication network NW which is not illustrated.

The wireless communication unit 210 performs wireless communication witha base station device BS which is accommodated in a mobile communicationnetwork NW in accordance with an instruction of the main control unit220. Using the wireless communication, the wireless communication unit210 transmits/receives various file data such as voice data and imagedata and electronic mail data or receives web data, streaming data, orthe like.

The display input unit 204 is provided with a display panel 202 and anoperating panel 203 as a so-called touch panel which displays an image(a still image or a moving picture) or text information under thecontrol of the main control unit 220 so as to visually transmitinformation to a user, and detects the user's operation on displayedinformation.

The display panel 202 uses a liquid crystal display (LCD), an organicelectro-luminescence display (OELD), or the like, as a display device.

The operating panel 203 is a device which is disposed to allow an imagedisplayed on a display surface of the display panel 202 to be visuallyrecognized and detects one or a plurality of coordinates which can beoperated by a finger of the user or a stylus. When the device isoperated by the finger of the user or the stylus, a detection signalwhich is generated based on the operation is output to the main controlunit 220. Subsequently, the main control unit 220 detects an operatingposition (coordinate) on the display panel 202, based on the receiveddetection signal.

As illustrated in FIG. 8, although the display panel 202 and theoperating panel 203 of the smart phone 200 exemplified as an embodimentof the photographing device of the present invention are integrated witheach other to constitute the display input unit 204, the operating panel203 is disposed to completely cover the display panel 202.

When such an arrangement is employed, the operating panel 203 may beprovided with a function of detecting the user's operation on a regionother than the display panel 202. In other words, the operating panel203 may include a detection region (hereinafter, referred to as adisplay region) on an overlapping portion which overlaps the displaypanel 202 and a detection region (hereinafter, referred to as a“non-display region”) for other outer peripheral portion which does notoverlap the display panel 202.

In the meantime, although the size of the display region and the size ofthe display panel 202 may completely coincide with each other, bothsizes do not necessarily coincide with each other. In addition, theoperating panel 203 may include two sensitive regions of an outerperipheral portion and an inner portion other than the outer peripheralportion. Moreover, a width of the outer peripheral portion isappropriately designed in accordance with the size of the housing 201.Moreover, as a position detecting system employed in the operating panel203, a matrix switch system, a resistive layer system, a surface elasticwave system, an infrared system, an electromagnetic induction system, oran electrostatic capacitive system may be exemplified, and any systemmay be employed.

The calling unit 211 includes the speaker 205 or the microphone 206 andconverts the user's voice input through the microphone 206 into voicedata to be processed by the main control unit 220 and outputs theconverted voice data to the main control unit 220, or decodes voice datareceived by the wireless communication unit 210 or the externalinput/output unit 213 and outputs the decoded voice data from thespeaker 205. Furthermore, as illustrated in FIG. 8, for example, thespeaker 205 may be mounted on the same surface as the surface providedwith the display input unit 204 and the microphone 206 is mounted on aside surface of the housing 201.

The operating unit 207 is a hardware key which uses a key switch andreceives an instruction from the user. For example, as illustrated inFIG. 8, the operating unit 207 is a push button type switch which ismounted on a side surface of the housing 201 of the smart phone 200 andturned on when the operating unit 207 is pressed by a finger and turnedoff by restoring force of a spring when the finger is removed.

The storing unit 212 stores a control program or control data of themain control unit 220, application software, address data to whichnames, phone numbers, or the like of communication counterparts arecorrelated, transmitted/received electronic mail data, web datadownloaded by web browsing or downloaded content data, and temporarilystores streaming data. Further, the storing unit 212 is configured by aninternal storing unit 217 which is equipped in the smart phone and anexternal storing unit 218 which includes a detachable external memoryslot. Furthermore, the internal storing unit 217 and the externalstoring unit 218 which configure the storing unit 212 are implemented byusing a storing medium such as a flash memory type, hard disk type,multimedia card micro type, or card type memory (for example, MicroSD(registered trademark) memory), a random access memory (RAM), or a readonly memory (ROM).

The external input/output unit 213 functions as an interface with allexternal devices which are connected to the smart phone 200 and isconfigured to be directly or indirectly connected to any other externaldevice by communication (for example, universal serial bus (USB) orIEEE1394) or a network (for example, Internet, wireless LAN, Bluetooth(registered trademark), a radio frequency identification (RFID), aninfrared data association (IrDA (registered trademark)), ultra wideband(UWB: registered trademark), or a ZigBee (registered trademark).

As external devices connected to the smart phone 200, a wired/wirelesshead set, a wired/wireless external charger, a wired/wireless data port,a memory card or a SIM (subscriber identity module) card/UIM (useridentity module) card connected through a card socket, an externalaudio/video device connected through an audio/video input/output (I/O)terminal, a wirelessly connected external audio/video device, awired/wirelessly connected smart phone, a wired/wirelessly connectedpersonal computer, a wired/wirelessly connected PDA, a wired/wirelesslyconnected personal computer, or an earphone may be exemplified. Theexternal input/output unit 213 may transmit data which is received fromsuch external devices to individual components in the smart phone 200and may also allow the data in the smart phone 200 to be transmitted toan external device.

The GPS receiving unit 214 receives GPS signals which are transmittedfrom GPS satellites ST1 to STn according to an instruction from the maincontrol unit 220 and performs a position measurement operationprocessing based on the received GPS signals to detect positionsincluding a latitude, a longitude, and a height of the smart phone 200.When the GPS receiving unit 214 may obtain positional information fromthe wireless communication unit 210 or the external input/output unit213 (for example, the wireless LAN), the GPS receiving unit 214 maydetect a position using that positional information.

The motion sensor unit 215 includes, for example, a three axisacceleration sensor and detects physical movement of the smart phone 200according to the instruction of the main control unit 220. When thephysical movement of the smart phone 200 is detected, the movementdirection or acceleration of the smart phone 200 is detected. Thedetected result is output to the main control unit 220.

The power supply 216 supplies power which is accumulated in a battery(not illustrated) to individual units of the smart phone 200 accordingto the instruction of the main control unit 220.

The main control unit 220 includes a microprocessor and operatesaccording to a control program or control data stored in the storingunit 212 and collectively controls individual units of the smart phone200. Further, the main control unit 220 is provided with a mobilecommunication control function to control individual units of acommunication system and an application processing function in order toperform voice communication or data communication through the wirelesscommunication unit 210.

The application processing function is implemented when the main controlunit 220 is operated according to the application software which isstored in the storing unit 212. The application processing functionincludes, for example, an infrared communication function which performsdata communication with a counterpart device by controlling the externalinput/output unit 213, an electronic mail function whichtransmits/receives an electronic mail, and a web browsing function whichbrowses a web page.

The main control unit 220 is provided with an image processing functionwhich displays an image on the display input unit 204 based on the imagedata (still image or moving picture data) such as received data ordownloaded streaming data. The image processing function refers to afunction of decoding the image data and performing image processings onthe decoded result to display the image on the display input unit 204 bythe main control unit 220.

The main control unit 220 executes a display control of the displaypanel 202 and an operation detection control which detects a user'soperation through the operating unit 207 and the operating panel 203. Byexecuting the display control, the main control unit 220 displays anicon to activate application software or a software key such as a scrollbar or displays a window for preparing an electronic mail. Here, thescroll bar refers to a software key for receiving an instruction to movea displayed portion of an image with respect to a large image which isnot covered by the display region of the display panel 202.

By executing the operation detection control, the main control unit 220detects the user's operation through the operating unit 207 or receivesan operation on the icon or the input of a character string of an inputsection of the window through the operating panel 203 or receives ascroll request of a displayed image through the scroll bar.

By executing the operation detection control, the main control unit 220is provided with a touch panel control function that controls asensitive region of the operating panel 203 or a display position of thesoftware key by determining whether the operating position of theoperating panel 203 is an overlapping portion (display region) whichoverlaps the display panel 202 or an outer peripheral portion(non-display region) which does not overlap the display panel 202 otherthan the overlapping portion.

The main control unit 220 may detect a gesture operation with respect tothe operating panel 203 and execute a predetermined function accordingto the detected gesture operation. The gesture operation refers to anoperation which draws a trace using a finger, designates a plurality ofpositions simultaneously, or a combination thereof to draw a trace forat least one of the plurality of positions, rather than a simple touchoperation of the related art.

The camera 208 includes constitutional elements other than the externalmemory control unit 20, the recording medium 21, the display controlunit 22, the display unit 23, and the operating unit 14 in the digitalcamera which is illustrated in FIG. 1. Captured image data which isgenerated by the camera 208 may be stored in the storing unit 212 oroutput through the external input/output unit 213 or the wirelesscommunication unit 210. Although the camera 208 is mounted on the samesurface as the display input unit 204 in the smart phone 200 illustratedin FIG. 8, the mounting position of the camera 208 is not limitedthereto and the camera 208 may be mounted on a rear surface of thedisplay input unit 204.

The camera 208 may be used for various functions of the smart phone 200.For example, an image which is obtained by the camera 208 may bedisplayed on the display panel 202 or the image of the camera 208 may beused as one of operation inputs of the operating panel 203. Further,when the GPS receiving unit 214 detects the position, the position maybe detected with reference to the image from the camera 208. Moreover,an optical axis direction of the camera 208 of the smart phone 200 maybe determined or a current usage environment may also be determined withreference to the image from the camera 208 either without using the3-axis acceleration sensor or using the 3-axis acceleration sensor. Ofcourse, the image from the camera 208 can be used in the applicationsoftware.

Positional information obtained by the GPS receiving unit 214, voiceinformation obtained by the microphone 206 (which may be textinformation obtained by performing a voice-text conversion by the maincontrol unit or the like), or posture information obtained by the motionsensor unit 215 may be added to the image data of a still image or amoving picture to be stored in the storing unit 212 or output throughthe external input/output unit 213 or the wireless communication unit210.

Also in the smart phone 200 configured as described above, the maincontrol unit 220 performs the processing illustrated in FIGS. 5 and 6 byusing the solid-state imaging elements 5 and 5 a as the imaging elementof the camera 208, so that high speed and highly precise phasedifference AF may be achieved.

As described above, the following matters are disclosed herein.

It is disclosed an imaging device, including: a sensor including aplurality of first phase difference detecting pixels which receives oneof a pair of luminous fluxes which have passed through different partsof a pupil area of an imaging optical system and is arranged in a rowdirection and a plurality of second phase difference detecting pixelswhich receives the other one of the pair of luminous fluxes and isarranged in the row direction; a defocus amount calculating unit whichcalculates a correlated amount of a first output signal group and asecond output signal group while shifting the first output signal groupof the plurality of first phase difference detecting pixels and thesecond output signal group of the plurality of second phase differencedetecting pixels in the row direction by an arbitrary amount tocalculate a defocus amount from a first shift amount of the first outputsignal group and the second output signal group when the correlatedamount is at a maximum; and a focus control unit which controls a focusstate of the imaging optical system based on the defocus amount, inwhich the defocus amount calculating unit changes an upper limit of ashift amount of the first output signal group and the second outputsignal group in accordance with at least one of an F value of theimaging optical system, a focal distance of the imaging optical system,and a position of a focus lens included in the imaging optical system.

The imaging device may have a configuration, in which the sensor is animaging element for imaging and phase difference detecting, including aplurality of imaging pixels which receives luminous fluxes passingthrough the pupil area of the imaging optical system and is twodimensionally arranged in the row direction and a column direction whichis perpendicular to the row direction, the first phase differencedetecting pixel and the second phase difference detecting pixel aredisposed in different rows, and the imaging device includes: a drivingunit which performs rolling shutter driving to change an exposure periodfor every row of pixels to read out a signal in accordance with a lightreceiving amount during the exposure from the pixels included in eachrow; and a shift amount calculating unit which calculates a second shiftamount of the first output signal group and the second output signalgroup in the row direction caused by the rolling shutter driving, from ashift amount of the output signal groups when a correlated amount of theoutput signal groups of the plurality of imaging pixels included in twoadjacent rows is at a maximum, and the defocus amount calculating unitchanges the upper limit of the shift amount in accordance with at leastone of the F value, the focal distance, and the position of the focuslens and the second shift amount.

The imaging device may have a configuration, in which the defocus amountcalculating unit determines a value obtained by adding the second shiftamount to the upper limit determined in accordance with at least one ofthe F value, the focal distance, and the position of the focus lens asthe upper limit of the final shift amount.

The imaging device may have a configuration, in which the shift amountcalculating unit selects a row including a phase difference detectingpixel which is an output source of the first output signal group and theimaging pixel and a row including a phase difference detecting pixelwhich is an output source of the second output signal group and theimaging pixel as the two adjacent rows.

It is disclosed a focus control method by an imaging device whichincludes a sensor including a plurality of first phase differencedetecting pixels which receives one of a pair of luminous fluxes whichhave passed through different parts of a pupil area of an imagingoptical system and is arranged in a row direction and a plurality ofsecond phase difference detecting pixels which receives the other one ofthe pair of luminous fluxes and is arranged in the row direction, themethod including: a defocus amount calculating step of calculating acorrelated amount of a first output signal group and a second outputsignal group while shifting the first output signal group of theplurality of first phase difference detecting pixels and the secondoutput signal group of the plurality of second phase differencedetecting pixels in the row direction by an arbitrary shift amount tocalculate a defocus amount from a shifted mount of the first outputsignal group and the second output signal group when the correlatedamount is at a maximum; and a focus control step of controlling a focusstate of the imaging optical system based on the defocus amount, inwhich in the defocus amount calculating step, an upper limit of a shiftamount of the first output signal group and the second output signalgroup is changed in accordance with at least one of an F value of theimaging optical system, a focal distance of the imaging optical system,and a position of a focus lens included in the imaging optical system.

It is disclosed an imaging device, including: an imaging element whichincludes a plurality of pixels which is two dimensionally arranged in arow direction and a column direction which is perpendicular to the rowdirection, the plurality of pixels including a plurality of imagingpixels which receives luminous fluxes which have passed through a pupilarea of an imaging optical system, a plurality of first phase differencedetecting pixels which receives one of a pair of luminous fluxes whichhave passed through different parts of the pupil area of the imagingoptical system, and a plurality of second phase difference detectingpixels which receives the other one of the pair of luminous fluxes; adriving unit which performs rolling shutter driving to change anexposure period for every row of the pixels to read out a signal inaccordance with a light receiving amount during the exposure from thepixels included in each row; a defocus amount calculating unit whichcalculates a correlated amount of a first output signal group and asecond output signal group while shifting the first output signal groupof the plurality of first phase difference detecting pixels which isincluded in one of two adjacent rows among rows of the pixels and asecond output signal group of the plurality of second phase differencedetecting pixels which is included in the other one of the two rows inthe row direction by an arbitrary amount to calculate a defocus amountfrom a first shift amount of the first output signal group and thesecond output signal group when the correlated amount is at a maximum; afocus control unit which controls a focus state of the imaging opticalsystem based on the defocus amount; and a shift amount calculating unitwhich calculates a second shift amount of the first output signal groupand the second output signal group in the row direction caused by therolling shutter driving, from a shift amount of the output signal groupsin the row direction when a correlated amount between the output signalgroups of the plurality of imaging pixels included in two adjacent rowsamong the rows of the pixels is at the maximum, in which the defocusamount calculating unit changes an upper limit of the shift amount ofthe first output signal group and the second output signal group inaccordance with the second shift amount.

The imaging device may have a configuration, in which the defocus amountcalculating unit determines a value obtained by adding the second shiftamount to a predetermined value as the upper limit of the shift amount.

The imaging device may have a configuration, in which the shift amountcalculating unit selects a row including a phase difference detectingpixel which is an output source of the first output signal group and theimaging pixel and a row including a phase difference detecting pixelwhich is an output source of the second output signal group and theimaging pixel, as the two rows for calculating the correlated amount.

It is disclosed a focus control method by an imaging device whichincludes an imaging element which includes a plurality of pixels whichis two dimensionally arranged in a row direction and a column directionwhich is perpendicular to the row direction, the plurality of pixelsincluding a plurality of imaging pixels which receives luminous fluxeswhich have passed through a pupil area of an imaging optical system, aplurality of first phase difference detecting pixels which receives oneof a pair of luminous fluxes which have passed through different partsof the pupil area of the imaging optical system, and a plurality ofsecond phase difference detecting pixels which receives the other one ofthe pair of luminous fluxes, the method including: a driving step ofperforming rolling shutter driving to change an exposure period forevery row of pixels to read out a signal in accordance with a lightreceiving amount during the exposure from the pixels included in eachrow; a defocus amount calculating step of calculating a correlatedamount of a first output signal group and a second output signal groupwhile shifting the first output signal group of the plurality of firstphase difference detecting pixels which is included in one of twoadjacent rows among rows of the pixels and a second output signal groupof the plurality of second phase difference detecting pixels which isincluded in the other one of the two rows in the row direction by anarbitrary amount to calculate a defocus amount from a first shift amountof the first output signal group and the second output signal group whenthe correlated amount is at a maximum; a focus control step ofcontrolling a focus state of the imaging optical system based on thedefocus amount; and a shift amount calculating step of calculating asecond shift amount of the first output signal group and the secondoutput signal group in the row direction caused by the rolling shutterdriving, from a shift amount of the output signal groups in the rowdirection when a correlated amount of the output signal groups of theplurality of imaging pixels included in two adjacent rows among the rowsof pixels is at the maximum, in which in the defocus amount calculatingstep, an upper limit of the shift amount of the first output signalgroup and the second output signal group is changed in accordance withthe second shift amount.

Any one of the disclosed matters provides an imaging device and a focuscontrol method which may efficiently perform an operation of a phasedifference amount to achieve high speed phase difference AF.

Although the present invention has been described above by the specificembodiments, the present invention is not limited to the embodiments butvarious modifications may be allowed without departing from a technicalspirit of the disclosed invention.

What is claimed is:
 1. An imaging device, comprising: a sensor includinga plurality of first phase difference detecting pixels which receivesone of a pair of luminous fluxes which have passed through differentparts of a pupil area of an imaging optical system and is arranged in arow direction and a plurality of second phase difference detectingpixels which receives the other one of the pair of luminous fluxes andis arranged in the row direction; a defocus amount calculating unitwhich calculates a correlated amount of a first output signal group anda second output signal group while shifting the first output signalgroup of the plurality of first phase difference detecting pixels andthe second output signal group of the plurality of second phasedifference detecting pixels in the row direction by an arbitrary amountto calculate a defocus amount from a first shift amount of the firstoutput signal group and the second output signal group when thecorrelated amount is at a maximum; and a focus control unit whichcontrols a focus state of the imaging optical system based on thedefocus amount, wherein the defocus amount calculating unit changes anupper limit of a shift amount of the first output signal group and thesecond output signal group in accordance with at least one of an F valueof the imaging optical system, a focal distance of the imaging opticalsystem, and a position of a focus lens included in the imaging opticalsystem.
 2. The imaging device of claim 1, wherein the sensor is animaging element for imaging and phase difference detecting, including aplurality of imaging pixels which receives luminous fluxes passingthrough the pupil area of the imaging optical system and is twodimensionally arranged in the row direction and a column direction whichis perpendicular to the row direction, the first phase differencedetecting pixel and the second phase difference detecting pixel aredisposed in different rows, and the imaging device includes: a drivingunit which performs rolling shutter driving to change an exposure periodfor every row of pixels to read out a signal in accordance with a lightreceiving amount during the exposure from the pixels included in eachrow; and a shift amount calculating unit which calculates a second shiftamount of the first output signal group and the second output signalgroup in the row direction caused by the rolling shutter driving, from ashift amount of the output signal groups when a correlated amount of theoutput signal groups of the plurality of imaging pixels included in twoadjacent rows is at a maximum, and the defocus amount calculating unitchanges the upper limit of the shift amount in accordance with at leastone of the F value, the focal distance, and the position of the focuslens and the second shift amount.
 3. The imaging device of claim 2,wherein the defocus amount calculating unit determines a value obtainedby adding the second shift amount to the upper limit determined inaccordance with at least one of the F value, the focal distance, and theposition of the focus lens as the upper limit of the final shift amount.4. The imaging device of claim 2, wherein the shift amount calculatingunit selects a row including a phase difference detecting pixel which isan output source of the first output signal group and the imaging pixeland a row including a phase difference detecting pixel which is anoutput source of the second output signal group and the imaging pixel asthe two adjacent rows.
 5. A focus control method by an imaging devicewhich includes a sensor including a plurality of first phase differencedetecting pixels which receives one of a pair of luminous fluxes whichhave passed through different parts of a pupil area of an imagingoptical system and is arranged in a row direction and a plurality ofsecond phase difference detecting pixels which receives the other one ofthe pair of luminous fluxes and is arranged in the row direction, themethod comprising: a defocus amount calculating step of calculating acorrelated amount of a first output signal group and a second outputsignal group while shifting the first output signal group of theplurality of first phase difference detecting pixels and the secondoutput signal group of the plurality of second phase differencedetecting pixels in the row direction by an arbitrary shift amount tocalculate a defocus amount from a shifted mount of the first outputsignal group and the second output signal group when the correlatedamount is at a maximum; and a focus control step of controlling a focusstate of the imaging optical system based on the defocus amount, whereinin the defocus amount calculating step, an upper limit of a shift amountof the first output signal group and the second output signal group ischanged in accordance with at least one of an F value of the imagingoptical system, a focal distance of the imaging optical system, and aposition of a focus lens included in the imaging optical system.
 6. Animaging device, comprising: an imaging element which includes aplurality of pixels which is two dimensionally arranged in a rowdirection and a column direction which is perpendicular to the rowdirection, the plurality of pixels including a plurality of imagingpixels which receives luminous fluxes which have passed through a pupilarea of an imaging optical system, a plurality of first phase differencedetecting pixels which receives one of a pair of luminous fluxes whichhave passed through different parts of the pupil area of the imagingoptical system, and a plurality of second phase difference detectingpixels which receives the other one of the pair of luminous fluxes; adriving unit which performs rolling shutter driving to change anexposure period for every row of the pixels to read out a signal inaccordance with a light receiving amount during the exposure from thepixels included in each row; a defocus amount calculating unit whichcalculates a correlated amount of a first output signal group and asecond output signal group while shifting the first output signal groupof the plurality of first phase difference detecting pixels which isincluded in one of two adjacent rows among rows of the pixels and asecond output signal group of the plurality of second phase differencedetecting pixels which is included in the other one of the two rows inthe row direction by an arbitrary amount to calculate a defocus amountfrom a first shift amount of the first output signal group and thesecond output signal group when the correlated amount is at a maximum; afocus control unit which controls a focus state of the imaging opticalsystem based on the defocus amount; and a shift amount calculating unitwhich calculates a second shift amount of the first output signal groupand the second output signal group in the row direction caused by therolling shutter driving, from a shift amount of the output signal groupsin the row direction when a correlated amount between the output signalgroups of the plurality of imaging pixels included in two adjacent rowsamong the rows of the pixels is at the maximum, wherein the defocusamount calculating unit changes an upper limit of the shift amount ofthe first output signal group and the second output signal group inaccordance with the second shift amount.
 7. The imaging device of claim6, wherein the defocus amount calculating unit determines a valueobtained by adding the second shift amount to a predetermined value asthe upper limit of the shift amount.
 8. The imaging device of claim 6,wherein the shift amount calculating unit selects a row including aphase difference detecting pixel which is an output source of the firstoutput signal group and the imaging pixel and a row including a phasedifference detecting pixel which is an output source of the secondoutput signal group and the imaging pixel, as the two rows forcalculating the correlated amount.
 9. A focus control method by animaging device which includes an imaging element which includes aplurality of pixels which is two dimensionally arranged in a rowdirection and a column direction which is perpendicular to the rowdirection, the plurality of pixels including a plurality of imagingpixels which receives luminous fluxes which have passed through a pupilarea of an imaging optical system, a plurality of first phase differencedetecting pixels which receives one of a pair of luminous fluxes whichhave passed through different parts of the pupil area of the imagingoptical system, and a plurality of second phase difference detectingpixels which receives the other one of the pair of luminous fluxes, themethod comprising: a driving step of performing rolling shutter drivingto change an exposure period for every row of pixels to read out asignal in accordance with a light receiving amount during the exposurefrom the pixels included in each row; a defocus amount calculating stepof calculating a correlated amount of a first output signal group and asecond output signal group while shifting the first output signal groupof the plurality of first phase difference detecting pixels which isincluded in one of two adjacent rows among rows of the pixels and asecond output signal group of the plurality of second phase differencedetecting pixels which is included in the other one of the two rows inthe row direction by an arbitrary amount to calculate a defocus amountfrom a first shift amount of the first output signal group and thesecond output signal group when the correlated amount is at a maximum; afocus control step of controlling a focus state of the imaging opticalsystem based on the defocus amount; and a shift amount calculating stepof calculating a second shift amount of the first output signal groupand the second output signal group in the row direction caused by therolling shutter driving, from a shift amount of the output signal groupsin the row direction when a correlated amount of the output signalgroups of the plurality of imaging pixels included in two adjacent rowsamong the rows of pixels is at the maximum, wherein in the defocusamount calculating step, an upper limit of the shift amount of the firstoutput signal group and the second output signal group is changed inaccordance with the second shift amount.